The present disclosure relates to power transmission components and heat transfer systems. Axle assemblies in wheeled vehicle drivetrains are known to employ a differential apparatus to permit an outer drive wheel to rotate at a greater velocity than an inner drive wheel when operating a vehicle through a turn. Differential apparatuses employ a pinion gear drivingly engaged with a ring gear, which in turn rotates a differential case having a number of bevel gears engaged with a pair of side gears, the side gears being coupled with a pair of axles. The differential apparatus is located within a carrier housing of the axle assembly. Conventionally, a sump in the carrier housing contains lubricant to reduce friction between surfaces including, but not limited to, the pinion gear and ring gear, and the pair of side gears and the bevel gears.
In conventional axle assemblies, the lubricant causes parasitic drag that is exaggerated when the ambient temperature of the carrier housing is reduced below typical summer operating temperatures, such as during operation in cold weather. Lubricant temperature effects the viscosity of the lubricant, such that cold weather operation of an axle assembly creates an increase in vehicle fuel consumption. During a cold weather warm-up cycle of an axle assembly, the lubricant may disperse heat generated between the moving parts at a rate which prevents the viscosity of the lubricant from decreasing for several hours, resulting in increased drag and fuel consumption for a prolonged period of time. Similarly, lubricant within a transmission or gear box may also cause parasitic drag that is heightened during cold weather.
Increasing the temperature of the lubricant disposed in the axle assembly and/or gear box to minimize or eliminate the duration of a warm-up cycle can reduce parasitic drag and increase fuel economy.